Blockages within the body can take various forms. For example, esophageal food impactions are one of the most common and dangerous emergencies in gastroenterology, with an annual incidence rate of at least 13/100,000 population (Longstreth, GIE; 2001); moreover, the incidence has been increasing in recent years due to the recent rise in eosinophilic esophagitis (Desai, GIE; 2005). Food impactions can occur when a bolus of swallowed food becomes lodged in the esophagus and is unable to pass spontaneously into the stomach. This occurs either when the swallowed bolus is too large or when there are diseases of the esophagus that narrow the esophageal lumen, such as GE reflux with a stricture or ring, an esophageal food allergy such as eosinophilic esophagitis with stricture or stenosis of the esophagus, a Schatzki's ring, esophageal webs or esophageal cancer. Motility disorders of the esophagus typically do not cause impactions.
Most impactions clear spontaneously, but a significant fraction (20%) will not and will require emergent endoscopic intervention to clear the blocked food. This can be dangerous, since emergency endoscopy with removal of food can result in serious complications including aspiration pneumonia, laceration of the esophagus with bleeding, or esophageal perforation which can result in sepsis and death. The complication rate of endoscopic clearance of a food impaction is approximately 3-5% and the mortality rate is unknown but several deaths have been reported (Simic, Am J Forensic Med Path; 198).
Food impactions present acutely and dramatically, with patients noting chest pain or pressure, inability to swallow, painful swallowing, a sensation of choking, and neck or throat pain. Retching and vomiting are also common, and patients can also experience breathing problems due to tracheal or airway compression, with stridor, coughing or wheezing being noted.
There are various endoscopic tools used to clear impactions but all have flaws and there is no current technique that is demonstrably better than any other. Food can sometimes be pushed blindly through the esophagus and into the stomach using the tip of the endoscope, but this technique is performed without vision of the more distal esophagus, so the endoscopist has no way of knowing what the esophagus looks like distal to the obstruction or what abnormalities exist. This technique can work well (Vicari, GIE; 2001), but because the technique is blind, can often result in esophageal laceration or perforation. Many endoscopists avoid blind pushing for this reason. Forceps including “rat-tooth” type designs, snares and variable wire basket designs can be used to break up food into smaller pieces for extraction, but these techniques are laborious, time-consuming and often fail.
Other extraction techniques can also be tried, particularly when the food bolus is not tightly wedged and is firm, or if the food contains bone or sharp surfaces. In this regard, baskets, snares, graspers, “pelican” forceps with longer arms, nets etc., can be used to remove food in whole or in pieces, but these techniques also frequently fail, and the patient is at risk for aspiration pneumonia if the pieces fall into the hypopharynx or mouth during the extraction attempts. If the food bolus is lodged proximally, then most of the above techniques will fail or are too dangerous to try. Endoscopic suction cannot be used for impactions, since chunks of food cannot be effectively suctioned through an endoscope, and also if suction fails to hold a bolus against the tip of the scope then a patient would be at high-risk for aspiration as the scope is withdrawn through the hypopharynx or mouth. Overtubes can be used if repeated endoscopic intubation is needed, but overtubes are uncomfortable, require deeper sedation and are dangerous in of themselves with risk of esophageal laceration and perforation.
Thus, it is important to provide mechanisms to clear blockages within the body. For example, within the field of esophageal food impaction, there is a need for effective and safer mechanisms to remove food stuck in the esophagus.